In clinical or private radiology departments, patients are examined by means of non-invasive techniques, such as X-ray imaging, computed tomography, magnetic resonance, ultrasound, etc.
The use of X-ray imaging in medical diagnosis is presently widespread. According to conventional techniques, an image is recorded by a radiographic film sandwiched between a pair of intensifying screens in a cassette. After exposure, the radiographic film is taken out from the cassette manually or the cassette containing the film is loaded in full daylight in a film handling and processing apparatus such as the Trimatic.TM. Automatic Processor, manufactured by Imation Corp. USA.
These films are very useful for the radiologists to examine the anatomy in detail. The same films can also be transported to other departments and other physicians. The films can be stored for years and retrieved whenever necessary for comparison with the current situation.
Problems arise when the same images must be available at two different locations at the same time for examination, or when the locations are so distant that the transport time becomes critical. The storage organization and storage area also pose a problem in some hospitals, where by preference the patient carries the films home to keep them. Typically, these films are even more difficult to retrieve, because the patient may have lost them. These problems can be solved by scanning and digitizing the films used for visual examination, directly as they are produced (developed and dry) or before they leave the radiology department, to produce an electronic image from the films. These electronic images can be stored by electronic means in digital format. Today, image processing can be performed on images in digital format, e.g., for semi-automatic comparison of older medical images on film with currently acquired data, the images of the older films must be made available in digital format as electronic images.
During recent years, various manufacturers of radiographic and photographic equipment have offered apparatus useful for the digitization of photographic images. Once the radiographic image is available in digitized form, such a document can be archived, retrieved and processed in any of the various ways offered by digital image processing apparatus, such as, for example, transmission over telephone line for real time, on-line conference or long-distance diagnosis. For this purpose, the film, which has been fed out of the developing machine, must be manually set at the predetermined position in the film digitizer. The main problem of this procedure consists in time and labor consumption required to carry out such manual operations. Also, when the film is processed manually, the film will be contaminated with finger marks, dust, or the like. Therefore, when an image signal is detected from the film and used during the reproduction of a visible radiation image, the image quality of the visible radiation image thus reproduced cannot be kept high.
U.S. Pat. No. 5,237,358 and EP 452,570 attempt to solve the above problem by disclosing a radiation image read-out apparatus comprising an automatic developing machine for carrying out a developing process on an image-wised silver halide film directly connected to a film digitizer such that it may directly receive the silver halide film having been fed out of the automatic developing machine. The film digitizer photoelectrically reads out the radiation image, which has been converted into a visible image during the developing process, from the silver halide film and thereby generates an image signal representing the radiation image.
The main problem arising with the use of the apparatus described above relates to the orientation of the radiographic film entering the digitizing apparatus. Errors in digitization can arise if the film is not correctly fed to the digitizer, that is, if the axis of the film is not exactly aligned with the longitudinal axis of the scanning device. Another problem relates to the dimension of the film. Most common radiographic film formats which are present on the market have widths from about 15 to about 35 centimeters and lengths from about 17 to about 43 centimeters. The automatic developers currently on the market are fed using the longest side as the leading edge. Thus, when using the apparatus described in the above mentioned patents, a scanning line length of about 43 cm is needed in order to have a digitizer able to operate with all radiographic film formats. This increases the difficulties of the scanning apparatus to provide a final electronic image with high resolution. Line scanning is performed by means of a sequence of pixels. The longer the line to be scanned, the more difficult it is to assure the correct orientation of the film with respect of the scanning line. Additionally, the number of pixels required for the scanning line increase with its length and this results in more expensive digitizing apparatus. A third problem relates to the synchronization of the radiographic film processor and digitizer speed. Usually, the speed of radiographic film processor is higher than the speed of the digitizer and this results in a reduction of productivity in the medical department.
U.S. Pat. No. 5,583,663 discloses a digitizer which attempts to solve the above mentioned problems by providing within the digitizer means for keeping the radiographic film in a vertical position on a horizontal plane while a carrier abuts against the rear edge of the film, thereby moving it forward the digitizing means. The digitizer can be associated to a film processor for receiving directly the processed film from the output of the processor or through a film feeder. The solution proposed by such a disclosure requires to put the digitizer in front of the processor, so increasing the working space required by the combination. Additionally, the structure of the digitizer is such that the digitizer dimensions are higher than conventionally available digitizer. Moreover, the absence of any means for keeping the film in a vertical position before entering the scanning line can easily promote the blending or skewing of the film, in particular for high dimension films, with a consequent jam of the system and damage to the film.
Accordingly, there is still a need for working method and a compact dedicated apparatus for easy, convenient and fully automated processing and digitizing of radiographic films which solves the above mentioned problems.